In postmodern times, social media is an integral part of informal sports like parkour. It potentially impacts physical activities as well as the assessment of one’s physical abilities and skills. Referring to the under-researched impact on the self-assessment, this study aims to examine if the parkour-related physical self-concept can be determined by social media use, as well as parkour-training aspects and sociodemographics. Two reference points of comparison have been considered, comparing one’s skills to real or virtual parkour communities. To address this research phenomenon, multiple linear regression analyses were conducted. The results showed that a high parkour-related physical self-concept (pkPSC) is primarily determined by the amount of time athletes put into their parkour activities. Furthermore, age and gender played an important role, indicating that being a young male appeared to be a main determinant for a higher pkPSC. Finally, posting parkour-related content in social media appeared to influence the pkPSC, although this finding might be interpreted as causality in both directions. The study identified real-life activities to be more important for the physical self-concept of traceurs; however, social media play a crucial role in the parkour community.